The goal of our research is the demonstration and characterization of central and peripheral neurotransmitter and drug receptors. In this respect, we have previously demonstrated and characterized the muscarinic antagonist receptor site, the benzodiazepine receptor, the GABA receptor, the nicotinic cholinergic receptor and the adrenergic receptor. In the past year, we have used the muscarinic agonist, cis-methyldixolone (CD) to label the agonist muscarinic receptor binding site. In addition, we have demonstrated the binding of nonbenzodiazepines to the benzodiazepine receptor. With these additional novel ligands, we hope to study the heterogeneity and regulation of the many neurotransmitter and drug receptors in the brain.